They also did an incredible deal regarding coffee with Vietnam, where both sides got a lot out of it. A very different way of doing trade, but GDR never really saw the true benefits of it as they only kicked in in the 90s.
It's also worth noting for the first 10+ years East Germany massively outperformed West Germany. The issue was that West Germany had huge resources pumped in, loans written off, huge trade support, while East Germany had huge resources sucked out. Stalin wanted/needed reparations, and the function of East Germany was to provide them, for the horrors/damage that the Germans state inflicted on the Soviet Union. That burden was not equally shared at all.
So it's a total apple and pears comparison. There is a legitimate argument that if money hadn't have been sucked out, or huge investment wasn't out in to the western state, or reparation due to the Soviet Union were shared fairly from all of Germany history looks markedly different. If the huge returns had been invested back into East Germany in the first decade + there's every chance they would have outdone West Germany, which may have slowed the brain drain.
Even the brain drain stuff, which is the real reason it failed compared to West Germany is more complex. It's not inherently a flaw in the system of lack of entrepreneurs. The Eastern state has a superior education system, in developing key skills, but simply couldn't afford to keep people. And the Western state could then cherry pick the best talent, having paid 0 to educate them, where the GDR spent hugely in doing so. That not a question of entrepreneurship or ideology. And it's a bit rich saying the state who was disproportionately educated the best people is the inferior state.